The present disclosure relates generally to communication systems. More particularly, the present disclosure relates to an interface between the public switched telephone network (PSTN) and another network generally requiring a bearer system.
Certain networks, such as on-board aircraft networks, require a bearer system to interface it to another network or telephone system. For example, the Rockwell Collins Passenger Systems Integrated Phone System (RCPSIPS) requires a bearer system to communicate with the public switched telephone network (PSTN). The RCPSIPS is an E1 data network that can initiate and receive phone calls on an aircraft. The RCPSIPS interfaces with the PSTN through a bearer system, such as a Satcom-based system to provide telecommunication between it and a ground telephone coupled to the PSTN.
With reference to FIG. 1, a conventional communication system 10 can be embodied as a PSTN coupled to an RCPSIPS. System 10 includes an integrated phone system 20, a Satcom system 32, a satellite 34, a PSTN 30 and a ground earth station 36. A telephone 38, modem or other communication device can be coupled to PSTN 30.
Integrated phone system 20 can be located on an aircraft, vehicle, or other structure. Integrated phone system 20 includes cabin telecommunications unit (CTU) 16, cabin distribution system (CDS) 14, and at least one aircraft telephone 12, modem, or other communication device. Integrated phone system 20 can operate according to the ARINC standard 746.
Integrated phone system 20 is coupled to public switched telephone network (PSTN) 30 via a bearer or Satcom-based system (e.g., Satcom system 32, satellite 34, and ground earth station 36). Aircraft telephone 12 can be a passenger handset that is connected to cabin distribution system 14. Cabin distribution system 14 is coupled to cabin telecommunications unit 16 which is coupled to Satcom system 32.
Cabin distribution system 14 can be, for example, a Rockwell Collins AVU, ADB, and optional PESC. Cabin telecommunications unit 16 can be manufactured, for example, by AT&T, MORS, and BAE (formerly, GTE). System 14 communicates to cabin telecommunications unit 16 via an E1 or other data link. To establish a telephone call, cabin telecommunications unit 16 communicates via Satcom system 32, satellite 34 and ground earth station 36 to PSTN 30. PSTN 30 communicates with a handset, such as, telephone 38.
When system 20 is demonstrated, such as at a trade show or otherwise to a customer, a Satcom-based system (system 32, satellite 34, and station 36) or other bearer system provides an interface for communications to PSTN 30 because a non-satellite based interface is generally not available to PSTN 30. A Satcom-based system must be employed even though system 20 is not being utilized in an aircraft or other vehicle isolated from land connections to PSTN 30. For example, when system 20 is demonstrated, system 32 provides connectivity to PSTN 30 through satellite 34 and station 36 as if system 20 is being utilized in an aircraft.
In the avionics business industry, demonstrations of system 20 are performed at WAEA and other shows and are evaluated by airplane manufacturers and airline customers. Such demonstrations require the establishment of an expensive Satcom-based system including system 32, satellite 34 and station 36. Manufacturers of systems, such as cabin telecommunication units (e.g. unit 16), also require a satellite-based system for demonstrations.
Conventional bearer systems are expensive and undesirable for several reasons. First, per call costs associated with using a Satcom-based system are expensive. Second, such Satcom-based systems are subject to service discontinuation and require antennas which must be serviced by qualified personnel. Third, such Satcom-based systems require expensive equipment which must be leased. Fourth, if a Satcom-based system is not available for various reasons, the demonstration of system 20 is seriously degraded.
Another conventional technique for demonstrating system 20 is by coupling it to simulation phone equipment, such as, systems manufactured by Tekelec or Idacom. The simulation systems are provided to simulate a Satcom-based system and a PSTN, but are incapable of establishing real telephone calls.
The simulation systems typically contain an integrated handset to which calls are directed. However, the simulation does not allow real phone calls to be demonstrated and evaluated on the PSTN. The simulation systems are relatively inflexible because they cannot simulate a busy phone, no answer conditions, other telephone status, etc. Further, the simulation systems are not capable of generating incoming phone calls or data calls. Accordingly, the above-listed aspects of integrated phone system 20 and its interaction with an actual PSTN 30 cannot be effectively demonstrated using Tekelec or Idacom systems.
Other communication systems have utilized bearer systems, such as, Terrestrial Flight Telephone Systems (TFTS) and North American Terrestrial Systems (NATS) systems. However, these systems suffer from similar demonstration disadvantages as Satcom-based systems because TFTS and NATS systems must be established to effectively demonstrate and evaluate the communication system.
Thus, there is a need for a bearer system which can be coupled between a public switched telephone network (PSTN) and an integrated phone system which does not require the expense, availability, and expertise associated with Satcom-based systems and other conventional bearer systems. Further, there is a need for a method of demonstrating an integrated phone system which can receive phone calls from a public switched telephone network (PSTN). Further still, there is a need for an E1 data system which can be easily coupled to a public switched telephone network (PSTN) for demonstration and evaluation purposes. Yet further, there is a need for a null bearer system that can support real telephone calls between an Integrated Phone System handset and any phone in the world without the need for a satellite-based system.